To activate the final smash in the online game "Super Smash Flash 2," press the special move button after destroying a Smash Ball. The "O" key is the special move button. If there is a second player, that player's special move button is the "1" key on the number pad.
"Super Smash Flash 2" is a free fan game published by McLeodGaming. The fighting game is loosely based on the "Super Smash Bros." series of games. As of September 2014, the game is still under active development and only a playable demo of the game has been released. The gameplay of the final release may be different.